Add support for GTX 1660

[Django149]

It would be great to add support for GTX 1660 and similar GPUs. Thanks!

[Mega4alik]

@Django149 thanks for the question. I will make flash-attention2 and kvikio optional in the next release so older GPUs can be supported.

[Mega4alik]

@Django149 kvikio and flash-attn are optional now and ollm should work on any device supported by HF transformers. Kindly update the ollm and try it!